In prior art, manure water containing animal manure, and livestock industry system process water containing blood from animal and fish generated in meat plants, fishery plants and the like, were often subjected to cleaning treatment by using the activated sludge method or the like; however, if cleaning with a flocculating agent were possible, this would be simple and very useful.
In addition, during disasters such as storms and earthquakes, if murky mud water or the like could be cleaned simply with a flocculating agent and used as water for daily use, this would also be very useful during disasters. Thus, the cleaning treatment of suspension water by a flocculating agent is characterized by the possibility of being carried out simply even without a special installation.
In prior art, as this type of flocculating agent, known were those having as a main component, for instance, aluminum sulfate, aluminum chloride, ferric chloride and the like. However, as the treated water becomes acidic with a number of flocculating agents used in prior art, treated water cannot be released directly due to issues of contamination of the environment, or the like, requiring separately a treatment for returning to a neutral pH region.
Thus, as flocculating agents reacting at neutral to alkaline with which treated water becomes also neutral, proposed are such flocculating agents in the following:
For instance, disclosed in Patent Reference 1 is a flocculating agent containing animal bone, comprising a dissolved bone solution obtained by dissolving fired pulverized animal bone powder in sulfuric acid or hydrochloric acid.
Disclosed in Patent Reference 2 is a flocculating agent comprising burnt food scrap ashes, animal bone powder and zinc dissolved by mixing with sulfuric acid or hydrochloric acid, and water.
Furthermore, recently, high molecular weight flocculating agents such as polyacrylamide or copolymers thereof have become commercialized and are used commonly. However, when using this high molecular weight flocculating agent, there is the inconvenience that the pH has to be adjusted beforehand. Therefore, for instance, flocculating agents comprising a silicon solution in which silicon dioxide has been dissolved, flocculating agents with silicon dioxide and calcium hydroxide as main components, and the like, have also been proposed (refer for instance to Patent Reference 3).
[Patent Reference 1] Japanese Patent Application Laid-open No. H1-274807
[Patent Reference 2] Japanese Patent Application Laid-open No. H4-7004
[Patent Reference 3] Japanese Patent Application Laid-open No. 2001-104711